Grinding mill



. Dec.A 30, 1924.

J. s. FAS-UNG .GRINDING MILL Filed' April 4.

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JOHAN S. FASTING, 0F VALBY, NEAR OPENHAGEN, DENEJIRK, ASSG-NOR TO F. L.SIVIIDTH t CO., OF NEW YOREL Y., CRPORATGN O?? NEW' JERSEY.

GRINDING MILL.

Application filed April 4,

To all wlw/m t may concer/n.'

Be it known that I, JOHAN S. Fnsrixe, a subject of the King of Denmark,residing at Monrads Alle 9, Valby, near Copenhagen, Denmark, haveinvented certain new and useful Improvements in Grinding Mills, of whichthe following is a speciiication, rei erence being had to theaccompanying drawing, forming a part hereof.

rlhis invention relates to grinding mills the type commonly known astube mills. heretofore constructed such a grinding mill has a relativelylong, cylindrical shell, sometimes of uniform diameter from end to endand sometimes with one portion of greater diameter than the otherportion, and supported at its ends by trunnions which rest in suitablebearing blocks. The trunnions are hollow in order toV permit theadmission at the feeding end'of the material to be ground and thedischarge at the other end of the ground material. rlhe cylinder,because of the bending moment to which it is subjected by reason of itsconsiderable length and of the weight of the Vcharge of grinding bodiesand material being` ground, is sometimes supported between its ends byexterior supporting rings which rest upon suitable bearing rolls. Adriving gear is also commonly applied to the cylinder by means of whichthe cylinder may be rotated. In order to permit the progressiveVreduction of the material being ground, it is also common to erectwithin .the cylinder one or more transverse partitions for the purposeof 'forming successive .grinding chambers to receive grinding bodies ofdifferent size or character,V the partitions being provided withsuitable openings through which the material may pass from one chamberto the next. Among those p skilled in the art, some of the disadvantagesof such grinding mills are recognized. Because of the considerablelength of the cylinder and the bending moment .and other stresses towhich it is subjected, the cylinder must be of great strength andtherefore must be constructed of relatively heavy metal, notwithstandingthe fact that the metal. is protected from wear internally by the liningof the cylinder. This is particularly true of the cylinders which haveportions of different diameters. The Weight due to the strength .ofmetal thus required adds to the power required for the operation of themill without proportionate results. 'The external. bearing of A S i923.sei-iai No. 629,301.

rings and their supporting rolls quickly wear out of true, causingvibration and demanding increased power for operation.. The endtrunnions are necessarily of relatively small diameter and thereforelimit to some extent the size of the pieces of material to be groundwhich can be fed into the cylinder at the feeding end. The partitionsare difficult of access for renewal andrepair and in order to permitaccess (since the hollow trunnions are too small to permit the passageof a man) there must be provided in each chamber a manhole, whichnecessarily weakens the shell somewhat, requiring still greater strengthof material, and brings about rapid wear internally because of theimpracticability of protecting completely the manhole cover'by lining.The considerable length of the cylinder gives importance to the longitudinal expansion and contraction of the cylinder under the constantlyvarying temperatures, particularly in the grinding of hot cementclinker.

It has been found, in the present invention, that the disadvantagesabove mentioned in the operation of grinding mills, can be overcomelargely and -economy in operation effected by dispensing with the endbearing trunnions and supporting the mill by reduced bearings, ofpracticable diameter, between its ends. Usually, for a mill of standardlength, it will be found sufficient to provide, between the extremi tiesVof the mill, two such bearings `forming middle or main grindingcompartment, a primary grinding compartment overhung at one end, andaseparating or screening compartment overhung at the other enc. Theseveral compartments communicate with each other through the hollowbearing members, which need not be of large diameter, since no largepieces of material will pass through them. The feed opening at one endand the discharge opening at the other end of the mill can be made ofsuch diameter as not only to permit the free introduction at the feedingend of lmaterial which is relatively coarse, but to permit the passageof a man so that the provision of a separate manhole in the cylindricalwall of either chamber is unnecessary. Since almost the entire end ofeach compartment or chamber is exposed, the bolts which hold theseparating plates and liner plates at, the disclirge end of eachcompartment aie readily accessible, easy to inspect and easyto keep inorder. The preliminary grinding chamber or compartment can be made oflarger diameter than the other compartments so as properly to receiveand crush the irregular and relatively large pieces of material whichmay be fed to it, suoli material being reduced in the preliminarygrinding compartment to .a substantially uiiifo m and smaller size sothat most of it will pass readily through the separator plate in thedischarge end of the preliminary compartment. The bendingV moment of themiddle and longer compartment of the mill is greatly reduced by theoverhung preliminary grinding and separating or screening compartmentskand the weight of material ein aloved for the Y L, Y Y .l

lustrated in the drawing, the mill comf prises a preliminary grindingcompartment a, relatively short in'lengthand of relatively largediameter, a main grinding compartment 6,'of such length as to effect thedesired reductionof the material, and a relatively short supplementalgrinding comlpartment c. YThe preliminary grinding compartment acomprises end plates a and a2, the former provided with a central feedopening a3 and the latter with a central discharge vopening a4, and acylindrical wall 0,5. Within the compartmentV and near its dischargeend, is aperforated separator plate ci which hason rits discharge side adischarge cone a7 and substantially radial ribs or vanes as which liftthe reduced ma-V terial which has passed through the perforations of theplate andh discharge it upon Vthecone a7 byV which it isLdirectedthrough 1 4 ythe dischaige opening a Y .The ,main grinding compartment balso comprises end plates and b2, the former ,provided with a centralfeed opening b3 and the latter with a central discharge opening b4, andacylindrical shell b5. It is further provided with a separating platewhich Vhas a discharge cone 57 and lifting ribs or Avanes 5,8 toedectthe discharge of the produced ymaterial which passes through theseparating plate 56. The compartment 55 may also be provided externallywith Va gear ring b9 by which the mill can be rotated.

The supplemental compartment V'c `.may

also comprise end plates cf and o2, Y' the former having a central feedopening 03 and the latter a central discharge opening c4; Thiscompartment also has between the end plates a cylindrical wall of, andVmay Vmembers al and e, which may be secured to the respectivecompartments by .bolts as at d and e', such bearing members being hollowso as to permit thepassage of material throughV the same, and beingreceived in bearing blocks and f which may be mounted on suitablepedestals f2 and f3;

fr feed chute g may beiprovided forv directing into the preliminarygrinding drum a the material to be ground'andfthe screening drum@ may beprovided withv a discharge Vchute g. Y Y Y lt will Vbe observed that thefeed'opening a3 of the preliminary grinding drum t can be made as largeas maybe desired so that the feeding of the material to he ground, evenin relatively large pieces, will not be interfered with. Such materialas has received, in the compartment ya, the grinding necessary to permitit to pass throughthe separating plate a, will be raised by the vaiiesor Yribs a? and, falling upon the cone al, willbe directed into andthrough the bearing member CZ, while, in like manner, the materialwhichhas been Y further reduced in the main vgrinding compartment b andhas passed .through the separating plate-bs, will be'raised .and discharged through-"the hollow', bearing inember e. Finally,`the material.which` may be f rther reduced in the screening drum c and passes throughthe separatiiigplate c, will be raisedV and discharged Vthrough thedischargeopening at. i

. It will be noted that the constructionshown permits of the securingVofV thej required strength without the employment of heavy'V iio metal,it being understood that the interior Y ,of each compartment isprotected by the usual lining, not necessary tobe shown. VThe feedopening of the preliminary drum `or compartment can be made as large asdesii-ed, not only to permit the feeding in of material in relativelylarge pieces, butvof f such size as to permit the passage of aman,thereby doing away with the necessity of providing a manhole in the sideWall of the drum, in order to give access tothe interior for purposes ofreplacement and repair. In like manner the openings offthe bearingmembers d and e and, ifnecessary, of thedisy charge end of thesupplemental comparu' ment, cani-be made-of such diameteras to permitthe passage of arman.

l claim as my invention:

iso p l. A grinding mill comprising a relatively long main grinding drumof relatively large diameter having end walls and a` cylindrical wall,hollow bearing members of relatively small diameter secured one to eachend wall of the main grinding drum, supplemental drums of relativelylarge diameter each having an end wall secured to the outer end of oneof the hollow bearing members, the end walls of the drum being eachprovided with an opening communieating with the interior of a hollowbearing member, the hollow bearing members being adapted to serve as themeans for supporting the drums and to permit material treated to passfrom one drum to another.

2. A grinding vmill comprising a relatively long main grinding drum ofrelatively large diameter having end walls and a cylindrical wall,hollow bearing members of relatively small diameter secured one to eachend wall of the main grinding drum, supplemental drums of relativelylarge diameter and relatively short length each having an end wallsecured to the outer end Vof one of the hollow-bearing members, abearing block for each of the hollow bearing members, the end walls oithe drums being each provided with an opening communicating with theinterior of a hollow bearing mem- Yber, the hollow bearing members beingadapted to serve as the means for supporting the drums and to permitmaterial treated to pass from one drum to another.

3. A grinding mill comprising a relatively long main grinding drum ofrelatively large diameter having end walls and a cylindrical wall,hollow bearing members of relatively small diameter secured one to eachend wall of the main grinding drum, supplemental drums of relativelylarge diameter and substantially equal relatively short length eachhaving an end wall secured to the outer end of one of the hollow bearingmembers, a bearing block for each of the hollow bearing members, the endwalls or' the drums being each provided with an opening communicatingwith the interior of a hollow bearing member, the hollow bearing membersbeing adapted to serve as the means for supporting the drums and topermit material treated to pass from one drum to another.

4. A grinding mill comprising a preliminary drum having end walls and acylindrical wall, a main grinding drum having also end walls and acylindrical wall, a supplemental grinding drum having end walls and acylindrical wall, hollow bearing members having their opposite endssecured respectively to the adjacent end walls of the preliminary drumand the main drum and the adjacent walls of the main drum and thesupplemental drum, and bearing blocks for said bearing members, thepreliminary drum having near its discharge end a separator plate withlifting ribs and a central discharge cone.

5. A grinding mill comprising a preliminary drum having end walls and acylindrical wall, a main grinding drum having also end walls and acylindrical wall, a supplemental grinding drum having end walls and acylindrical wall, hollow bearing members having their opposite endssecured respectively to the adjacent end walls of the preliminary drumand the main drum and the adjacent walls of the main drum and thesupplemental drum, and bearing blocks for said bearing members, the maindrum having near its discharge end a separating plate with lifting ribsand a discharge cone.

This specilication signed this 15th day of March A. D. 1923.

JOHAN S. FASTING.

